Smart socks tracking every step you run may sound like a Silicon Valley spoof, or a sinister, 85% polyester alternative to the US National Security Agency's Prism scheme.

The Sensoria Smart Sock Fitness Tracker is a real thing, though, and appealing enough to have persuaded 450 people to pledge more than $72k on crowdfunding website Indiegogo to get the socks as soon as they go on sale in March 2014.

The company behind the socks, Heapsylon, is aiming to raise $87k to make the tracker, and with 16 days left in its campaign, looks set to reach the finish line early.

200 people pledged $99 to get the cheapest price for the socks, with latecomers able to pay $119. The keenest joggers can pay $499 to become an "Alpha Runner" and get a prototype tracker in December 2013, to help Heapsylon in its final tests of the product.

The socks will include textile sensors placed under each foot, to measure how they land on the ground with the aim of warning runners of "heel striking or excessive forefoot running" that could lead to injuries.

They will ship with a Bluetooth-enabled magnetic anklet to snap onto the cuff of a sock, with the wearers able to download an app for iPhone or Android smartphones to analyse their runs.

"When you go home you won't just look at pretty charts; you'll be able to analyze in detail what you have done well, for how long and what action you can take to get to the next level," promises the Indiegogo listing.

Heapsylon is also hoping other developers will make apps that use data from the Sensoria socks: seven have already agreed to pay $399 for a software development kit, which will be launched in September.

Companies like Nike, Fitbit, Jawbone and Withings have been selling a range of fitness-tracking devices, from clip-on pedometers to wristbands, with their own companion apps. Standalone apps like Moves offer similar features using the smartphone's accelerometer rather than additional hardware.

There is even a fitness-tracking device for dogs called FitBark, with its own crowdfunding campaign on Indiegogo's rival Kickstarter. After six days, it has already raised more than $50k against an original target of $35k.

The Sensoria smart socks look set to hit their own milestone well ahead of time too. And in answer to the obvious question: yes, they can be washed. Although in a reminder of the limitations of technological progress, they're not quite smart enough to walk themselves to the washing basket.